It'd be nice to be able to add more expressions to the variable testing tab

[christianp]

I was sure I'd already written this years ago, but I can't find it.

The variable testing tab fulfils two roles at the moment: specifying a condition that the variables must satisfy, and for experimenting while authoring to see how often a certain situation arises.

For the experimentation use, it'd be nice if you could write several expressions, and get a summary of how many times each of them was satisfied.